Sheet clamping device



July 3, 1962 M. E. CHICK SHEET CLAMPING DEVICE Filed July 27, 1961 FIG. 4

FIG. 5

INVENTOR. MELVIN E. CHICK ATTORNEY United States Patent Of'icc 3,041,795 SHEET CLAMPlNG DEVICE Melvin E. Chick, Bartlesville, kla., assignor of one-half to Burt McClintock, Bartlesville, Okla. Filed July 27, 1961, Ser. No. 127,310 Claims. (Cl. 51-194) This invention relates to apparatus for clamping or securing an abrasive sheet (for either abrading or polishing) to a truncated conical rotatable support, commonly used in the shoe repair industry.

Shoe repair machines are equipped with various rotatable members (wheels) which rotate on a common shaft generally powered by an electric motor. One such member is a sanding wheel which comprises a conical metal support coaxial with the shaft to which it is attached and provided with a removable abrasive sheet. The sheet wears out frequently and must be replaced.

Present shoe repair machines are equipped with an abrasive wheel comprising a cylindrical member bored to fit the end of the mandrel on which other wheels, such as but-ling, polishing, and the usual shoe repair devices are located. This cylindrical member is provided with a coaxial conical sheet support and is firmly attached by set screws to the mandrel. The outer cylindrical surface of said member is threaded to receive a threaded collar which has an inwardly tapered end to fit the conical support. By screwing the collar against the sheet on the support and tightening set screws in the collar against the member inside the collar, the sheet is held firmly to the support. With the foregoing arrangement, the task of changing the abrasive sheet is somewhat tim consuming and tedious. The collar must be set tight against the sheet when the sheet is installed and to do so requires a punch and hammer to move the collar into tight engagement with the supported sheet. The sheet of abrasive wears only a short time and requires frequent replacement. To remove the worn out sheet or to replace a sheet with a diiferent grade of abrasive sheet, the collar must be turned or screwed away from the sheet by means of a hammer and punch or nail set, at least for a turn or two.

This invention is directed to an improved device for attaching, clamping, or securing sheet material, such as abrasive cloth or paper, to a conical support attachable to a mandrel, such as a shoe machinery mandrel.

Accordingly, it is an object of the invention to provide an improved device for attaching or securing an abrasive sheet to a rotatable conical (truncated) support. Another object is to provide means for securing sheet material to a rotatable conical support which is simple, economical to construct, and time saving in removing and replacing the sheet material. Other objects of the invention Will become apparent to one skilled in the art upon consideration of the accompanying disclosure.

The device of the invention utilizes in combination, a support in the form of a truncated cone attached axially to a cylindrical member having an axial bore for mounting on a mandrel; a cylindrical collar loosely slidable on said member; first means mounted on said member and having a free end extending over a section of the smaller end of said support, biased therefrom and flexibly displaceable against said support for clamping sheet material thereto; second means mounted on said collar for displacing said first means against said support and fixing said collar on said member; and third means for attaching said member to said mandrel.

The first means comprises a sheet holder disposed in a longitudinal groove in the cylindrical member, attached thereto near the end opposite said support, spring biased in spaced apart relation to said support, but displaceable 3,041,795 Patented July 3, 1962 against same. A fiat spring shaped properly serves th required function.

The second means comprises a cam, provided with a hand lever, disposed in a slot and groove in the collar surrounding the cylindrical member, operable when th arm is in said groove to displace the first means firmly against the sheet support to hold said sheet firmly thereon and fix said collar to said member.

The third means may comprise any suitable means for attaching a hollow cylinder to a shaft, such as set screws countersunk in said cylinder and adapted to move radially against said shaft when set.

A more complete understanding of the invention may be had by reference to the accompanying schematic drawing of which FIGURE 1 is a pictorial view of the device of the invention in assembled form; FIGURES 2 and 3 are pictorial views of the principal members of the device of FIGURE 1; FIGURE 4 is a fragmentary partial section taken on the line 44 of FIGURE 1; FIGURE 5 is a side view of the spring sheet holder of the device of FIGURE 4; and FIGURE 6 is a plan view of a sheet of abrasive shown in operating position in FIGURE 1.

Referring to- FIGURE 1, numeral 10 designates the end section of a rotatable shaft or mandrel of a shoe repair machine. On the smaller section 12 of the shaft is positioned a cylindrical member 14 which is attached firmly to the shaft to provide a mounting or support member for collar 16. Bored cylinder 14 is integral with sheet support member 18 which is directly under sheet 20 and forms a firm backing therefor.

The detail of the device is best understood by reference to FIGURES 2, 3, and 4 wherein truncated conical support 18 is shown integral and coaxial with cylindrical member 14. FIGURE 2 shows conical support 18 without abrasive sheet thereon with a shallow groove 22 in the surface thereof in alignment with groove 24. A sheet holder or clamp in the form of a flat spring 26 is attached by a screw 28 to the bottom of groove 24. The shape of spring 26, as shown more clearly in FIG- URE 5, biases the free end away from support 18. The free end of spring 26 is provided with an arcuate section 30 which follows the conical contour of support 18 and forms a sheet holding element when urged or displaced radially inwardly toward support 18.

Cylindrical member 14 is provided with a bore 32 to slidably engage shaft section 12. One or more set screws 34 are threaded in member 14 so as to be setable on shaft section 12. Radial holes 36 in collar 16 provide access to screws 34 when the assembly is complete.

The actuating means for sheet holders 26 and 30 comprises cam 38 including cam head 40 and cam lever or arm 42. The cam is pinioned in a longitudinal slot and groove combination in collar 16 by pin 44. Raising of arm 42 to extend radially away from the assembly releases spring 26 and arcuate section 30 from sheet 20, because of the biasing action of spring 26 and the eccentricity of the cam, shown best in FIGURE 4. When the cam 38 is in the closed position as shown in the drawing, it clamps collar 16 firmly to cylindrical member 14; however, set screws 46 threaded in the collar and directed radially toward member 14 may be provided to insure against slipping of the collar during operation of the abrasive wheel." It should be noted that collar 16 is inwardly tapered on the end adjacent cone 18 to conform to the slope of the cone so as to permit extension of the collar over element 30 for protective purposes.

Diametrically opposite groove 24 in member 14 is a similar groove 50 and a sheet guide 52 which is similar in shape to spring sheet clamp or holder 26. An arcuate section 54 on the end extending over conical support 18 serves to guide sheet 20 into position. This sheet guide is not essential to effective operation of the device but it facilitates positioning of the paper on support 18.

Abrasive sheet (FIGURE 6) is an evolution of a cone (truncated) and is provided with an overlap section 56 which is approximately the size and shape of shallow groove 22 in cone 20. This groove allows overlapping without producing a bulge on the conical abrasive surface.

Spring clamping member 26 should be sufficiently strong to apply proper holding or clamping pressure on sheet 20 when cam 38 is locked in position. The free endof this spring clamp does not necessarily require the arcuate section shown, variations therein being operative. It is essential that sufiicient contacting surface is provided between the free end (clamping section or element) and the sheet on support 18. A pair of conical prongs on the end of spring 26 would also serve the purpose.

Thus, it can be seen that the quick clamping or attaching device of the invention is a substantial improvement over the prior art device which requires screwing a collar against the sheetand conical support, using a punch and hammer to finish the last turn or two of the collar, and again using the punch and hammer to unfasten the sheet for removal. In contrast, the device described requires merely raising the cam lever to back the cam off the clamping spring which immediately releases the sheet without moving the collar away from the sheet. When attaching a new sheet, the sheet is easily slid into place with the fingers and the cam lever is hand operable with ease.

A device substantially that shown in the drawing has been in operation for a period of testing on a shoe repair machine and has been found to be a time saver and a great convenience compared to the device supplied with the machine and described herein.

The details shown on the drawing and described herein illustrate the preferred form of the invention. Certain modifications thereof will become obvious to one skilled in the art and are within the scope of the invention.

I claim:

1. Apparatus for attaching an abrasive sheet to a rotatable truncated conical support axially mounted on a cylindrical member having an axial bore for mounting on a mandrel comprising in combination a cylindrical collar having a bore loosely fittingsaid cylindrical member and slidable thereon; means for attaching said cylindrical member to said mandrel; a longitudinal groove in the outer surface of said member; a flat springin said groove attached to said member adjaoentthe end opposite said conical'support and-free at the opposite end, said spring being biased away from a section of the bottom of said groove adjacent said conicalsupport, the free end of said spring extending longitudinally alongand axially spaced from a section of said support so as to be displaceable onto said support; a longitudinal slot in said collar extending completely therethru in a section of the end adjacent said support; a groove in the outer surface ofsaid collar extending longitudinally away from said slot; and a cam rotatably mounted in said slot and provided with an arm rotatable into said groove so as to force said cam radially inwardly against that section of said spring spaced from the bottom of said groove and press the free end of said spring against said support.

2. The apparatus of claim 1 including an arcuate member on the free end of said spring extending transversely thereof and spaced uniformly from said conical support so as to provide substantial gripping area for holding said abrasive sheet on said support.

3. The apparatus of claim 2 including a shallow groove extending longitudinally along the surface of said conical support in alignment with said spring for accommodating overlap of said sheet whereby said arcuate member contacts the overlap of said sheet.

4. The apparatus of claim 1 including a second longitudinal groove in said cylindrical member diametrically opposite first said groove and a paper guide in said second groove attached to said member and having a free arcuate end transverse to said groove and uniformly spaced from said support a distance slightly greater than the thickness of said sheet.

5. The apparatus of claim 1 wherein said collar overlaps said free end of said spring.

6'. Apparatus comprising in combination a rotatable truncated conical support axially mounted on a cylindrical member having an axial bore for mounting on a mandrel; a cylindrical collar having a bore loosely fitting said cylindrical member and slidable thereon; first means mounted on said cylindrical member having a free end extending over a section of the smaller end of said conical support, spaced therefrom and flexibly displaceable against said sup-port; second means mounted on said collar for displacing said first means against said support and fixing said collar on said cylindrical member; and third means for attaching said cylindrical member to said mandrel.

7. The apparatus of claim 6 wherein said collar extends over and covers said free end.

8. The apparatus of claim 7 including an arcuate section on said free end uniformly spaced from said collar and extending transversely of the axis of said conical support.

9. The apparatus of claim 7 including a paper guide afiixed to said cylindrical member having a free end extending along and slightly spaced'from said conical support, said paper guide also being covered --by said collar.

10. The apparatus of claim 6 wherein said first means comprises a clamp spring biased away from said conical support by a flat spring mounted in a groove in said cylindrical member; and said second means comprises a cam mounted in said collar and rotatable by means of an arm so as to depress said clamp against said support, said arm being rotatable into a longitudinal groove in said collar to effect the depressing and fixing of said collar on said cylindrical member.

No references cited. 

